EP0689990B1 - Noise reduction device for rotorcraft - Google Patents

Noise reduction device for rotorcraft Download PDF

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Publication number
EP0689990B1
EP0689990B1 EP95109510A EP95109510A EP0689990B1 EP 0689990 B1 EP0689990 B1 EP 0689990B1 EP 95109510 A EP95109510 A EP 95109510A EP 95109510 A EP95109510 A EP 95109510A EP 0689990 B1 EP0689990 B1 EP 0689990B1
Authority
EP
European Patent Office
Prior art keywords
air
rotorcraft
blade
ejection
noise reduction
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP95109510A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0689990A1 (en
Inventor
Akira Azuma
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kawada Industries Inc
Original Assignee
Kawada Industries Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kawada Industries Inc filed Critical Kawada Industries Inc
Publication of EP0689990A1 publication Critical patent/EP0689990A1/en
Application granted granted Critical
Publication of EP0689990B1 publication Critical patent/EP0689990B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C27/00—Rotorcraft; Rotors peculiar thereto
    • B64C27/32—Rotors
    • B64C27/46—Blades
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C23/00—Influencing air flow over aircraft surfaces, not otherwise provided for
    • B64C23/06—Influencing air flow over aircraft surfaces, not otherwise provided for by generating vortices
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T50/00—Aeronautics or air transport
    • Y02T50/10—Drag reduction

Definitions

  • the present invention relates to a device for reducing noise and vibration caused by rotation of rotor blades of a rotorcraft such as a helicopter, and for improving kinetic efficiency thereof.
  • the direction of air discharged from the nozzle is also fixed in the rearward direction which is intended to inject the air into the center of the tip vortex along the track of the blades.
  • the position of the blade tip vortex and the intensity and size thereof vary with the flight velocity, attitude and mode of the rotorcraft, and with the environmental wind conditions. Furthermore, the blade tip vortex, after being generated, grows successively in a conical shape, increasing its vortex core size gradually. Therefore, even if the air is ejected from the blade tip rearward along the track of the blade, it is not always possible to effectively supply the air toward the center of the vortex. That is, there still exists a problem in the above mentioned arrangement with the fixed position nozzles which cannot effectively reduce the intensity of the blade tip vortex.
  • a noise reduction device for a rotor-craft which comprises an air-producing means for producing compressed air, the air-producing means being arranged in the airframe of the rotorcraft; rotor blades connected to a drive shaft, each of the rotor blades having an air supply passage formed therein to communicate with the air-producing means, thereby to permit the flow of the compressed air; and ejection nozzles for ejecting the compressed air supplied through the air supply passage out of the rotor blades, the ejection nozzles being arranged at the blade tips and on the trailing edges of the rotor blades to eject the compressed air generally downwardly in the rotational direction.
  • a device for controlling boundary layer energization in a rotorcraft which comprises an air-producing means for producing compressed air, the air-producing means being arranged in the airframe of the rotorcraft; a drive shaft driven by an engine of the rotorcraft, the drive shaft having a first air supply passage formed therein so as to connect with the air-producing means thereby to permit the flow of the compressed air; rotor blades connected to the drive shaft, each of the rotor blades having a second air supply passage formed therein to communicate with the first air supply passage of the drive shaft; and ejection nozzles for ejecting the compressed air supplied through the second air supply passage out of the rotor blades, the ejection nozzles being arranged at the blade tips and on the trailing edges of the rotor blades to eject the compressed air in the rotational direction.
  • the ejection nozzles at the blade tips eject the compressed air to the radial direction of the rotor blades, that is, outside the blade tips thereby blowing the blade tip vortex away from the vicinity of the blade tip and out of the rotational area of the rotor blade. Consequently, since a blade tip vortex is moved out of the vicinity of the blade tip of the following rotor blade, a direct collision on the vortex generated by the rotation of the preceding rotor blade can be avoided.
  • the ejection angle adjusting device in the ejection nozzles can be operated to eject the compressed air upward or downward. Consequently, the blade tip vortex is moved upward or downward of the rotating plane of the rotor blades, therefore the interference of the blade tip vortex with the rotor blade can be avoided.
  • the intensity of the blade tip vortex can be significantly reduced and the strong vortex core can be defused, then the blade vortex interference itself does not occur, and the accompanying problems of noise and vibrations can be solved.
  • the tip vortex when the tip vortex is forced to be located above or below the rotor blade plane of rotation by ejecting air upward or downward using the ejection angle control device, or the blade tracking pass is changed upward or downward by the reaction of upward or downward ejection of air, it is possible to accomplish this task only by the air jet ejected from the nozzle at the blade tip.
  • the air ejected upward or downward from the jet nozzle on the trailing edge of the blade tip end can suitably control the blade tracking pass alteration and separate the position of the tip vortex and its pass from the plane of rotation.
  • Figures 1 and 2 show a partially sectioned plan view and a sectional view of a rotor blade interior arrangement.
  • the rotor blade 1 of this system contains an air supply passage 3 to supply compressed air furnished from the fuselage 2 toward the blade tip.
  • an air pressure control device 8 equipped with various valving devices necessary to connect to the air compressor of the engine 7 is located in the fuselage 2.
  • the air supplied by the engine 7 passes through the air pressure control device 8 described earlier and the duct 10 installed in the drive shaft 9.
  • the compressed air with predetermined jet pressure and flow rate is supplied to the air ejecting nozzles 6a and 6b on the blade tip 4a and on the trailing edge 4b near the blade tip from the air supply passage 3 within the blade 1.
  • control air passage 11 is provided in parallel with, but separate from, the air supply passage 3 through the inside the drive shaft 9 from the air pressure control system 8.
  • the end of the control air passage 11 is connected to the ejection angle control device 5 of the air ejecting nozzles 6a and 6b located within the blade tip 4a and the trailing edge 4b near the blade tip.
  • the ejection angle control device 5 of the air ejecting nozzles 6a and 6b consists of, as shown in Fig. 2 for an example, a rubber or plastic air tube 12 located on near side of the air ejecting nozzles 6a and 6b.
  • the control air passage 11, located in parallel with the air supply passage 3, is connected to this air tube 12.
  • the ejection angle control device 5 transmits the required amount of air into the air tube 12 through the control air passage 11, or adjusts the amount of air in the air tube 12 by suction as necessary.
  • the size of the throat area of the air ejecting nozzles 6a and 6b is either increased or decreased, consequently the direction of the air jet from the nozzles 6a and 6b can be properly controlled.
  • the air tube 12 contains bellows 13 on the inner side of the blade, or on the connecting side of the control air passage 11, and the bellows 13 maintains the height of the tube 12 in the lowered form as shown by the solid lines when the amount of air in the tube 12 is relatively small.
  • the air transmitted through the air supply passage 3 is ejected nearly horizontally from the nozzles 6a and 6b.
  • the bellows 13 expands as shown by the broken lines, providing the required height.
  • the jet of air can be directed downward from the nozzles 6a and 6b because the air in the air supply passage 3 flows into the nozzles 6a and 6b over the tube 12.
  • a pivotable flap 14 about the hinge 15 is provided onto the control air passage 11.
  • the free end of the flap 14 is placed on the bellows 13 in the air tube 12. Then, when the bellows 13 in the air tube 12 expands, the compressed air passing through the air supply passage 3 does not directly strike the bellows 13, and the air flows out following the inclined surface of the flap 14 over the air tube 12, thus preventing damages to the air tube 12.
  • the ejection angle control device 5 of the air tube 12 is easily provided using a freely flexible air pressure activated mechanism within the limited small space of a rotor blade cross section. In addition, because the mechanism causes little troubles during the usage, it can be utilized relatively trouble free.
  • the ejection angle control device 5 is not necessarily limited to the air tube described above. Besides the above design, it can be a jet ejection nozzle of a cylinder shape, for example, with a linkage mechanism placed in the blade and controlled from the cockpit to properly change the ejection angle.
  • the ejection angles from the ejection nozzles at the blade tip 4a and the trailing edge 4b near the blade tip were discussed as the horizontal direction and the downward direction from the blade.
  • the ejection angle is not limited to those two directions described, and it is possible to direct the jet of air to upward or rearward.
  • the jet of air from the nozzle 6a at the blade tip 4a blows the air located outside of the blade tip 4a away to the outside of the blade tip tracking pass, thus preventing the air around the blade tip to flow into the downstream side of the blade tip.
  • the air jet from the nozzle 6b on the trailing edge 4b near the blade tip blows away the vortex generated in the vicinity of the blade tip trailing edge, and the blade tip vortex 20a is forced to be relocated to outside of the plane of rotation of the rotor blade 1A.
  • the blade tip vortex 20a generated in this fashion is not directly slapped by the following blade 1B, thus the noise can be reduced greatly.
  • the jet ejection angles of nozzles 6a and 6b at the blade tip 4a and on the trailing edge 4b near the blade tip are adjustable in a preferred embodiment, by ejecting jet of air from the preceding blade 1A in upward or downward, the blade tip vortex 20b can be relocated to above or below the blade plane of rotation D, as shown in Fig. 5.
  • the tip vortex 20b generated outside of the plane of rotation of the blade 1A comes into the plane of rotation of the following blade 1B due to the various flight conditions such as the fuselage flight attitude, flight mode, and strength of the relative wind, the following blade 1B avoids the tip vortex 20b, thus preventing the generation of noise.
  • the tip vortex 20c comes into the rotational area of the following blade 1B as shown in Fig. 6, and there is a chance that the following blade 1B slaps the tip vortex 20c. Accordingly, in such a case, eject a jet of air upward or downward from the nozzles of the blade 1B before the blade 1B strikes the tip vortex 20c, and change the rotational tracking pass of the following blade 1B by the reaction of the jet.
  • the system can definitely prevent the noise and vibration due to the tip vortex interaction.
  • the tip vortex 20c generated by the rotation of the preceding blade 1A comes into the rotational range of the following blade 1B due to flight or air current conditions, and causes interaction in rotation. Since the interaction is known to occur within the certain limited azimuth position of the following blade 1B, eject the jet of air upward or downward by operating the ejection angle control device 5 of the blade 1B from the cockpit before the blade 1B enters this azimuth position.
  • moving the blade tip upward or downward to avoid a collision with the tip vortex 20c at the same time, moving the tracking pass of the tip vortex 20c upward or downward , the slapping of the tip vortex by the following blade can be avoided.
  • the present invention can change the tracking pass and the position of tip vortex generation by a simple technique, and move the blade tip upward or downward from the normal pass. Thus, it can precisely avoid the collision of the rotor blade with the tip vortex.
  • the previous method of preventing the tip vortex noise generation by changing the blade pitch angle, in addition to the pitch angle variation to fly the rotorcraft by the operation of the swash plate provides rotor blade pitch angle changes which are higher orders than the rotational speed, using heavy-duty steering actuators of high frequency.
  • the present invention does not require such complex systems as described, and has advantage of eliminating noise and vibration due to the blade tip vortex by the simple operation of this system.

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  • Engineering & Computer Science (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Toys (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)
EP95109510A 1994-06-30 1995-06-20 Noise reduction device for rotorcraft Expired - Lifetime EP0689990B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP170431/94 1994-06-30
JP6170431A JP2951540B2 (ja) 1994-06-30 1994-06-30 回転翼航空機の低騒音化装置

Publications (2)

Publication Number Publication Date
EP0689990A1 EP0689990A1 (en) 1996-01-03
EP0689990B1 true EP0689990B1 (en) 1998-09-23

Family

ID=15904794

Family Applications (1)

Application Number Title Priority Date Filing Date
EP95109510A Expired - Lifetime EP0689990B1 (en) 1994-06-30 1995-06-20 Noise reduction device for rotorcraft

Country Status (4)

Country Link
US (1) US5562414A (ja)
EP (1) EP0689990B1 (ja)
JP (1) JP2951540B2 (ja)
DE (1) DE69504915T2 (ja)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101134504B (zh) * 2006-08-25 2012-05-30 波音公司 控制机翼漩涡的主动系统和方法
DE102021110538A1 (de) 2021-04-26 2022-10-27 Dr. Ing. H.C. F. Porsche Aktiengesellschaft Luftfahrzeugpropeller und Luftfahrzeug

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US5791875A (en) * 1996-09-10 1998-08-11 Mcdonnell Douglas Helicopter Co. Tip vortex reduction system
US5813625A (en) * 1996-10-09 1998-09-29 Mcdonnell Douglas Helicopter Company Active blowing system for rotorcraft vortex interaction noise reduction
US6234751B1 (en) 1997-06-05 2001-05-22 Mcdonnell Douglas Helicopter Co. Oscillating air jets for reducing HSI noise
US6543719B1 (en) 1997-06-05 2003-04-08 Mcdonnell Douglas Helicopter Co. Oscillating air jets for implementing blade variable twist, enhancing engine and blade efficiency, and reducing drag, vibration, download and ir signature
FR2782307B1 (fr) 1998-08-17 2000-10-13 Onera (Off Nat Aerospatiale) Procede pour la reduction du bruit d'interaction pales-tourbillons engendre par une voilure tournante
US6138955A (en) * 1998-12-23 2000-10-31 Board Of Supervisors Of Louisiana State University And Agricultural And Mechanical College Vortical lift control over a highly swept wing
US6283406B1 (en) * 1999-09-10 2001-09-04 Gte Service Corporation Use of flow injection and extraction to control blade vortex interaction and high speed impulsive noise in helicopters
EP1780387A3 (en) * 2000-09-05 2007-07-18 Sudarshan Paul Dev Nested core gas turbine engine
US6671590B1 (en) 2001-04-30 2003-12-30 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Method and system for active noise control of tiltrotor aircraft
US6478541B1 (en) 2001-08-16 2002-11-12 The Boeing Company Tapered/segmented flaps for rotor blade-vortex interaction (BVI) noise and vibration reduction
US6948906B2 (en) * 2003-04-02 2005-09-27 University Of Maryland Rotor blade system with reduced blade-vortex interaction noise
US7100875B2 (en) * 2004-02-20 2006-09-05 The Boeing Company Apparatus and method for the control of trailing wake flows
US7661629B2 (en) * 2004-02-20 2010-02-16 The Boeing Company Systems and methods for destabilizing an airfoil vortex
US7134631B2 (en) * 2004-06-10 2006-11-14 Loth John L Vorticity cancellation at trailing edge for induced drag elimination
US7231997B2 (en) * 2005-03-25 2007-06-19 Aerofex Corporation Hybrid drive powered lift platform
DE102006008434A1 (de) * 2006-02-23 2007-09-06 Airbus Deutschland Gmbh Vorrichtung zur Reduzierung des aerodynamisch bedingten Lärms an der Seitenkante einer Stellfläche, insbesondere einer Hochauftriebsfläche eines Flugzeugs
US7686253B2 (en) 2006-08-10 2010-03-30 The Boeing Company Systems and methods for tracing aircraft vortices
JP4912955B2 (ja) * 2007-05-28 2012-04-11 株式会社東芝 空力騒音低減装置、流体機器、移動体および回転機器
US9505492B2 (en) * 2012-02-23 2016-11-29 Sikorsky Aircraft Corporation Mission adaptive rotor blade
JP5956803B2 (ja) * 2012-03-29 2016-07-27 一般社団法人日本航空宇宙工業会 飛行体の高揚力装置
CN104326082A (zh) * 2014-10-20 2015-02-04 清华大学 直升机及其桨叶
WO2017123294A1 (en) * 2015-10-17 2017-07-20 Sikorsky Aircraft Corporation Reduced blade vortex interaction
US10532805B2 (en) * 2016-09-20 2020-01-14 Gulfstream Aerospace Corporation Airfoil for an aircraft having reduced noise generation
US11014661B2 (en) * 2016-10-24 2021-05-25 Sikorsky Aircraft Corporation Tip jet orifice for aircraft brown out mitigation
FR3066756A1 (fr) * 2017-05-24 2018-11-30 Airbus Helicopters Procede et systeme d'anticipation de l'entree dans un domaine de vortex par un giravion
CN108170939B (zh) * 2017-12-26 2020-04-24 南京航空航天大学 一种基于后缘襟翼的降低旋翼噪声的方法及系统
CN108216617B (zh) * 2017-12-29 2020-04-24 厦门大学 一种抑制直升机桨-涡干扰噪声的方法
FR3111619B1 (fr) * 2020-06-17 2022-12-23 Airbus Helicopters Pale de giravion munie de cavités, giravion équipé d’une telle pale et procédé d’atténuation d’un bruit
US20200339248A1 (en) * 2020-06-30 2020-10-29 Papa Abdoulaye MBODJ Boundary layer suction design by using wingtip vortex for a lift-generating body
CN112896503B (zh) * 2021-03-18 2022-12-13 厦门大学 一种能够抑制桨尖涡的直升机旋翼桨叶
CN113335509B (zh) * 2021-06-03 2022-07-01 南京航空航天大学 一种直升机桨叶的流动控制方法

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101134504B (zh) * 2006-08-25 2012-05-30 波音公司 控制机翼漩涡的主动系统和方法
DE102021110538A1 (de) 2021-04-26 2022-10-27 Dr. Ing. H.C. F. Porsche Aktiengesellschaft Luftfahrzeugpropeller und Luftfahrzeug
US11679863B2 (en) 2021-04-26 2023-06-20 Dr. Ing. H.C. F. Porsche Aktiengesellschaft Aircraft propeller and aircraft
DE102021110538B4 (de) 2021-04-26 2024-02-29 Dr. Ing. H.C. F. Porsche Aktiengesellschaft Luftfahrzeugpropeller und Luftfahrzeug

Also Published As

Publication number Publication date
JP2951540B2 (ja) 1999-09-20
EP0689990A1 (en) 1996-01-03
US5562414A (en) 1996-10-08
JPH0811792A (ja) 1996-01-16
DE69504915T2 (de) 1999-03-18
DE69504915D1 (de) 1998-10-29

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